1. Technical Field
This invention relates generally to an apparatus and method for transforming perspective-distorted circular field of view images into non-distorted, normal perspective images having various orientations, rotations, and magnifications within the field of view.
2. Related Information
Camera viewing systems are used in abundance for surveillance, inspection, security, and remote sensing. Remote viewing is critical, for example, for robotic manipulation tasks. Close viewing is necessary for detailed manipulation tasks wile wide-angle viewing aids positioning of the robotic system to avoid collisions with the work space. Most of these systems use either a fixed-mount camera with a limited viewing field to reduce distortion, or they utilize mechanical pan-and-tilt platforms and mechanized zoom lenses to orient the camera and magnify its image. In the applications where orientation of the camera and magnification of its image are required, the mechanical solution is large in size and can subtend a significant volume making the viewing system difficult to conceal or use in close quarters. Several cameras are usually necessary to provide wide-angle viewing of the work space.
In order to provide a maximum amount of viewing coverage or subtended angle, mechanical pan/tilt mechanisms usually use motorized drives and gear mechanisms to manipulate the vertical and horizontal orientation. An example of such a device is shown in U.S. Pat. No. 4,728,839 issued to J. B. Coughlan, et al, on Mar. 1, 1988. Collisions with the working environment caused by these mechanical pan/tilt orientation mechanisms can damage both the camera and the work space and impede the remote handling operation. Simultaneously, viewing in said remote environments is extremely important to the performance of inspection and manipulation activities.
Camera viewing systems that use internal optics to provide wide viewing angles have also been developed in order to minimize the size and volume of the camera and the intrusion into the viewing area. These systems rely on the movement of either a mirror or prism to change the tilt-angle of orientation and provide mechanical rotation of the entire camera to change the pan angle of orientation. Additional lenses are used to minimize distortion. Using this means, the size of the camera orientation system can be minimized, but “blind spots” in the center of the view result. Also, these systems typically have no means of magnifying the image and or producing multiple images from a single camera.
References that may be relevant to the evaluation of the present invention are U.S. Pat. Nos. 4,772,942 issued to M. J. Tuck on Sep. 20, 1988; 5,023,725 issued to D. McCutchen on Jun. 11, 1991; 5,067,019 issued to R. D. Juday on Nov. 19, 1991; and 5,068,735 issued to K. Tuchiya, et al on Nov. 26, 1991.
Accordingly, it is an object of the present invention to provide an apparatus that can provide an image of any portion of the viewing space within a selected field-of-view without moving the apparatus, and then electronically correct for visual distortions of the view.
It is another object of the present invention to provide horizontal orientation (pan), vertical orientation (tilt) and rotational orientation (rotation) of the viewing direction with no moving mechanisms.
It is another object of the present invention to provide the ability to magnify or scale the image (zoom in and out) electronically.
It is another object of the present invention to provide electronic control of the image intensity (iris level).
It is another object of the present invention to be able to accomplish pan, tilt, zoom, rotation, and iris adjustments with simple inputs made by a lay person from a joystick, keyboard controller, or computer controlled means.
It is also an object of the present invention to provide accurate control of the absolute viewing direction and orientations using said input devices.
A further object of the present invention is to provide the ability to produce multiple images with different orientations and magnifications simultaneously from a single input image.
Another object of the present invention is to be able to provide these images at real-time video rates, e.g. thirty transformed images per second, and to support various display format standards such as the National Television Standards Committee RS-170 signal format and/or higher resolution formats currently under development.
It is also an object of the present invention to provide a system that can be used for automatic or manual surveillance of selected environments, with optical views of these environments corrected electronically to remove distortion so as to facilitate this surveillance.
These and other objects of the present invention will become apparent upon consideration of the drawings hereinafter in combination with a complete description thereof.